Chart Word Problem GMAT, GRE Quant

A shoe cobbler charges n dollars to repair a single pair of loafers. Tomorrow, he intends to earn 240 dollars repairing loafers. If he were to reduce his fee per pair by 20 dollars, he would have to repair an additional pair of the loafers to ear the same amount of revenue. How many pair of loafers does he intend to repair tomorrow?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

So, let’s assign x to represent the number of pair of loafers he intends to repair tomorrow. 

nx = 240

Reducing his fee by $20 would result in the need to repair an additional pair of shoes:

(n –20)(x + 1) = 240

We can also use testing to find the correct answer choice.

Only answer choice C results in the correct amount of revenue.